The writer of Halo 5 that made Cortana evil. His name... Is Brian Reed. Back in Halo 5's development, they trashed the story, and one day, he got hired. Every good idea, developed character, gone. Then, when Halo 5 was released, there were those who followed.

In those days, the fandom had two major complaints, the campaign, and the multiplayer. They almost have good multiplayer, but the campaign, they couldn't come close. It was already established story.